[Spalunkeldusch]

Hello,

So I have a 2006 E91 320d. Originally, it comes with M-ASK Business navigation system and a small, useless screen.

Probably 3 years ago I have decided that I want something more modern instead of current small OEM screen, and installed large Android screen, by replacing the small OEM one.

Everything was alright. The Android uses the sound from oem AUX port. I connect to the Android via Bluetooth from my phone, and play music without any issues.

Going further, since I have base sound system, I've decided to install amp+subwoofer in the trunk of the car. Handed the car to a guy, who did all the wiring through the carpet of the car. The amp is basically to enhance the subwoofer that is in the trunk, and not the oem car speakers.

Everything was fine, had to hissing, no issues, literally all good, up until I wanted another upgrade -> retrofitted Hi-Fi tweeters near side mirrors.
Tweeters connected directly to a dedicated port near the door speakers. At first - everything seemed to be fine, tweeters are working.

However, I've noticed a static "hiss" whenever the volume is turned higher. The hiss seems to be coming from tweeters, because I did not hear it at all before installing tweets. The more volume I raise, the louder the hiss becomes.

I've contacted the guy who installed subwoofer and amp for me, he says it's possible that the Android unit gives a bad signal, therefore the hiss appears. But that can't be true. Why there was no hissing before tweeters install?

Since android is using AUX as a main source to play music, I've decided to switch from AUX source to FM, which would basically start using the OEM m-ask radio as a source, however, I noticed that the hiss is still present even when using FM, so I come to conclusion that the android is not the issue.

Since amp does not power oem speakers and only the subwoofer in the trunk (separate box installed), and android is not the issue. I have two possible options:

1. Hi-Fi tweeters that I have bought (they're taken from other E90) are faulty.
or
2. M-ASK system is too "weak" in terms of audio quality and hissing is expected with it.

Do you think I would notice any change if I replace M-ASK Business system to CCC Professional? This would require me to get professional radio and a CCC block to replace with my current M-ASK Business block. + some coding as well.

I don't want to commit spending money on CCC block, if I won't be sure that it would solve the hissing issue.